Well, let me explain why I said never.
It's rather simple, you can't commercially release someone else's property, even if you mod(ify) it. It's still their property. GTA is Rock* Games's property, and the App Store is a commercial platform. Therefore, it'll never happen that the game with the mod appears on iTunes. It's basically the same reason why music videos on Youtube disappear or get blocked. Someone who doesn't own the rights to the content still published it. Just that on iTunes the order is different, content is first checked by Apple before it's published. Therefore it can't even happen that the modded game slips into the store even just for a brief amount of time before it gets removed. Hence I summarized that with never.